I'm trying to set up a Y-splitter, basically it has two extruders sharing a single nozzle.

Seems that for this to work, I basically have to retract filament when its not being used out of the shared filament channel (i.e. put it in its "rest" position) - this is done by retracting filament, say 20cm.

Most of the links I find on google use Cura or Slic3r, where they have distinct sections for "Extruder Start" and "Extruder End" Gcode - so the start gcode would advance filament 20cm, and end gcode would retract filament 20cm. This way only one filament is in the nozzle at any one time.

But I am unable to figure out how to do this in Ideamaker, as there is only a single "Extruder Switch Gcode" box, i.e. gcode that runs at the start of extruder switching...but where do I put the gcode that runs when that extruder is done? (i.e. before it switches to the other extruder/runs start Gcode for the next extruder)